I think it'd behoove you to know the limitations of these cameras. These are all Point and Shoot cameras. They're made to do just that. They're cheap but easy. However, you'll be limited. In your case, there aren't any manual modes for you to adjust the settings on your photos. In some cases, that can be good. However, you'll be relying on your camera's programming to take pictures for you under all situations.
Having said that, here's some of the advantages for each of the cameras. Pick the one that best fits you
Canon Powershot A495
37 - 122mm (35mm equiv)
This lens would be great for taking landscape photos. I'm pleasantly surprised to see this in a sub $100 camera
F3.0-5.8
Decent aperture. That's the type of aperture I'd expect from a camera in this price range. This basically screams "Don't take photos in low light"
ISO sensitivity up to 1600
ISO just tells you how sensitive your camera can be to low light levels. The higher the number, the more sensitive it will become to light
Scene modes:
There are a lot of them. I really like how there's a setting for fireworks. Perhaps one of these will serve you well one day.
Weight (no batt) 135 g (4.8 oz)
A bit on the heavier side for these types of cameras. If you're going to EDC it, carry it closer to your waist so the weight is better distributed.
Dimensions 94x 62 x 31 mm
Info taken from:
http://www.dpreview.com/news/1001/10010503canona490_a495.asp
Sony DSC-S2100
35mm - *
Couldn't find this info
F 3.1 - 5.6
Practically the same as the Canon. Same advantages/disadvantages apply
ISO up to 3200
A full step higher than the Canon. While I wouldn't recommend taking a photo at this ISO, it's worth it if you want to preserve that memory.
Scene Modes
Sony lists something called a twilight mode. I assume that's similar if not the same as Canon's fireworks mode.
Weight 4.8oz. (137g)
Same comments apply from Canon
Dimensions 97.6mm x 61.0mm x 27.2mm
Info taken from: (I love it when manufacturers give this much info on their products!)
http://www.sonystyle.com/webapp/wcs...10151&langId=-1&productId=8198552921666073319
Nikon Coolpix L22 Definitely don't get this one. The aperture is horrible compared to the other two and it's ridiculously heavy
37-134mm
Very Similar to the Canon. Same comments apply
F 3.1-6.7
Ouch! That's horrible when compared to the other two.
ISO up to 1600
Same comments apply
Scene Modes
Couldn't find info
Weight 183 g (6.5 oz)
With all due respect, you're a bloody idiot if you EDC a camera this heavy. Carry a decent cameraphone instead!
Dimensions 97.7 x 60.5 x 28.3 mm
Info taken from:
http://www.photographyblog.com/reviews/nikon_coolpix_l22_review/specifications/
Hopefully this helps. Feel free to reply back to this thread if you have any other queries